1. Field
One or more embodiments described herein relate to a device for winding an electrode plate.
2. Description of Related Art
Some secondary batteries provide a power storage device that provides a high energy density for storing energy by converting electric energy into chemical energy. Secondary batteries are configured to be rechargeable, unlike primary batteries that are not configured to be rechargeable, and are widely used in integrated circuit (IC) devices, such as cellular phones, notebook computers, tablet PCs, or the like. Recently, due to an increase in oil prices, electric vehicles are drawing attention and there is an increasing tendency of using secondary batteries as power sources for electric vehicles. With such a trend, some secondary batteries may need to provide such characteristics as high density, high capacity, high output, stability, and so on.
For example, in order to fabricate a high-capacity secondary battery, an electrode plate coated with as much electrode active material as possible (or practical) may be wound in the same or substantially the same volume of a can. In order to increase an amount of the electrode active material coated on the electrode plate, an area occupied by a current collector within the can may be reduced.
In order to reduce the area of the current collector, a multi-tab electrode assembly structure has recently been developed. For example, a multi-tab electrode assembly includes multiple tabs (a plurality of tabs) formed by aligning uncoated portions having or notched in multiple tab shapes (a plurality of tab shapes) during winding of an electrode plate. Since the multi-tabs serve as the current collector, the area of the current collector occupied in the can may be greatly reduced, as compared to an area of a current collector that does not include a multi-tab electrode.
In order to form a current collector having a particular (or set) shape in an electrode plate, such as a tab, a notching device based on or utilizing a molding method or a laser method, may be used. The notching device, which may include an unwinding unit, a punching unit and a winding unit, punches a base material supplied as a reel in a suitable or desired shape, winds the punched base material in a reel-type (or reel-kind) and supplies the reel-type (or reel-kind) base material to a winding device for fabricating an electrode assembly.
When the base material having a notched tab of the winding device travels (or is utilized) in roll-to-roll equipment, the tab may be folded when the base material passes a roller due to drooping or sagging of the tab as a result of gravity or fluctuation. The folding of the tab may cause damage to a final product, making it difficult to use the completed electrode assembly. In addition, the folding of the tab may cause problems in adjusting the tension and traveling speed of the base material, thereby adversely or negatively affecting the yield of final products.